Northern Ireland`s police were pelted with bricks and bottles and used water cannon to disperse crowds as violence broke out at a traditional Orange Order parade in Belfast on Monday.
The July 12 parade, held a day late this year because it fell on a Sunday, is Northern Ireland`s most contentious loyalist march, commemorating a 1690 victory of Protestant King William III over Catholic rival James II.
Marchers waving British Union Jack flags and wearing traditional loyalist symbols confronted police as they were prevented from entering the majority Catholic and nationalist Ardoyne area, a flashpoint for violence in the past.
One man was arrested after his car drove into a crowd outside the Ardoyne shops, trapping a teenage girl beneath the vehicle.
Police lifted up the car to free the injured girl, who was aged about 16 and was receiving treatment at the scene, police said.
"I would appeal for calm and ask that space be given to the medics attending the scene," assistant chief constable Stephen Martin said in a statement. "An investigation into the circumstances is now underway."
Riot police used water cannon to disperse marchers in a standoff in the unionist Woodvale Road area, as the crowd sang loyalist songs.
Eight police officers were injured, according to the Police Service of Northern Ireland.
A decision not to permanently fly the Union Jack over Belfast`s town hall, and curtailment of parades going through Catholic areas have sparked anger among some in the unionist community.
The Orange Order condemned the violence and called for calm.
"Those involved in violence should desist," said a spokesman for the Grand Orange Lodge of Ireland.
"It is not only counter-productive but also plain wrong. Such actions are only strengthening the hand of those who wish to further curtail our parades. We call on anyone engaged in illegal behaviour to stop immediately."
Last year`s July 12 was peaceful but over 800 police officers were injured during street battles in 2013 that recalled the worst days of "The Troubles" -- a period of sectarian strife in Northern Ireland in which over 3,000 were killed.
A landmark 1998 peace deal established a power-sharing government including both nationalists and unionists, but tension remains between the two communities and "peace walls" separate rival neighbourhoods in Belfast.